This invention relates to circuit breakers. It is a general object of this invention to provide new and improved circuit breaker mechanisms.
This invention, especially suitable for use in circuit breaker housings of a size commonly used by the electrical industry for its residential circuit breakers, does not rely critically on housing dimensions for its functionality. Thus, it can perform consistently in a variety of housing designs. Advantageously, a circuit breaker should be quick-made, quick-break in action, must be trip-free under overload conditions, and it should trip instantaneously (magnetically) at about 1200 to 1500 percent of breaker rating, preferably without requiring elaborate and thus costly magnetic structures. It should further lend itself to inexpensive manufacture and easy assembly.
In order to permit reasonable housing wall thicknesses and operating clearances in a variety of housings, the width of the mechanism must be minimized. Magnetic operation at low current values requires low unlatching forces. "Switching duty" requirements call for higher contact pressures and contact "wipe" action. Functioning in a variety of housings, and, hence adaptability to varying locations and forms of line and load connections and handle configurations, suggests either an integrated mechanism--trip unit assembly; or a mechanism and a trip unit, the spatial relationship between which is not overly critical. This invention is based on the latter concept.